ScienceDaily (Mar. 7, 2011) — An international team of researchers including professor Emmett Duffy of the Virginia Institute of Marine Science has published a comprehensive new analysis showing that loss of plant biodiversity disrupts the fundamental services that ecosystems provide to humanity.
Plant communities — threatened by development, invasive species, climate change, and other factors — provide humans with food, help purify water supplies, generate oxygen, and supply raw materials for building, clothing, paper, and other products.
The 9-member research team, led by professor Brad Cardinale of the University of Michigan, analyzed the results of 574 field and laboratory studies — conducted across 5 continents during the last 2 decades — that measured the changes in productivity resulting from loss of plants species. This type of “meta-analysis” allows researchers to move beyond their own individual or collaborative studies to get a much more reliable global picture. Their study appears in the March special biodiversity issue of the American Journal of Botany.
“The idea that declining diversity compromises the functioning of ecosystems was controversial for many years,” says Duffy, a marine ecologist who has studied the effects of biodiversity loss in seagrass beds. “This paper should be the final nail in the coffin of that controversy. It’s the most rigorous and comprehensive analysis yet, and it clearly shows that extinction of plant species compromises the productivity that supports Earth’s ecosystems.”
The team’s analysis shows that plant communities with many different species are nearly 1.5 times more productive than those with only one species (such as a cornfield or carefully tended lawn), and ongoing research finds even stronger benefits of diversity when the various other important natural services of ecosystems are considered. Diverse communities are also more efficient at capturing nutrients, light, and other limiting resources.
The analysis also suggests, based on laboratory studies of algae, that diverse plant communities generate oxygen — and take-up carbon dioxide — more than twice as fast as plant monocultures.
The team’s findings are consistent for plant communities both on land and in fresh- and saltwater, suggesting that plant biodiversity is of general and fundamental importance to the functioning of Earth’s entire biosphere.
Duffy, Loretta and Lewis Glucksman Professor of Marine Science at VIMS, says the team’s findings are important locally because estuaries like Chesapeake Bay are naturally low in plant diversity, making them especially vulnerable to ecological surprises resulting from loss of species.
“Salt marshes and seagrass beds depend largely on one or a few species of plants that create the habitat structure,” says Duffy. “When such species are lost, low diversity means there is often no one else to take their place…”
the rest of the article can be found at sciencedaily
A San Francisco-based monitor has identified trace amounts of radioactive iodine, cesium and tellurium isotopes in the air, consistent with the Japanese nuclear incident. But they are at levels far too small to pose a risk to human health, according to the U.S. Environmental Protection Agency.
“The radiation levels are hundreds of thousands to millions of times below levels of concern,” according to an EPA statement released Tuesday.
In a typical day, Americans receive doses of radiation from natural sources like rocks, bricks and the sun that are about 100,000 times higher than what is arriving in California from Japan, according to its analysis. The levels from Japan are 100,000 times lower than the radiation received from taking a round-trip international flight, the agency said.
The San Francisco monitor is one of four West Coast RadNet air-monitor filters; the others are in Anaheim, Riverside and Seattle. The samples were captured Friday and sent to EPA scientists for detailed lab analysis, which was completed Monday night.
A fifth monitor, based in Hawaii, also detected minuscule levels of a radioactive isotope. The identification and analysis is not yet complete.
Specifically, the San Francisco monitor found these levels of radiation, measured in Picocuries per meter, cubed: Cesium-137: 0.0013; Tellurium-132: 0.0075; Iodine-132: 0.0066; and Iodine-131: 0.068.
(what these reassurances fail to mention is that the rocks and bricks cool off when the sun sets, and the flight will eventually end…the radioactive fallout from japan will eventually end, too…someday…also, radioactive materials tend to accumulate in the body…ed.)
Work resumes to stabilise Japan nuclear plant
Work to stabilise Japan’s stricken Fukushima nuclear plant has resumed after work was suspended due to a plume of black smoke seen coming from a reactor.
Japan’s nuclear safety authority said two employees were taken to hospital after being exposed to radiation.
The optimism of Japanese officials surveying efforts to halt a nuclear crisis in Japan on Thursday contrasted with dire warnings from U.S. experts about the possibility of dangerous levels of radiation spreading across a large area.
The Fukushima nuclear power plant’s reactors have sat idle for the past five days, but not without tremendous action around them. Japanese officials said they are close to returning a power supply to the reactors, which would allow them to restart the regular cooling process. When an earthquake and tsunami leveled much of the nearby seaboard last week, other measures had to be taken to keep the fuel roads cooled.
But as that problem approached a resolution, a new problem confronted the plant. Old nuclear fuel roads resting in pools of sixty feet of water may be sitting in empty baths. Exposure to air would cause the fuel rods to heat up, burn and send a steady, sustained amount of radiation into the atmosphere.
“We believe that around the reactor site there are high levels of radiation,” Gregory Jaczko, head of the Nuclear Regulatory Commission, told a House Energy and Commerce subcommittee hearing. “It would be very difficult for emergency workers to get near the reactors. The doses they could experience would potentially be lethal doses in a very short period of time.”
Reported by the New York Times:
On Thursday morning a spokesman for Tokyo Electric Power, the Daiichi plant operator, and a spokesman for Japan’s nuclear regulatory agency, denied Mr. Jaczko’s account, saying the situation at reactor No. 4 had not changed and that water remained in the spent fuel storage pool. But both officials said the situation was changing and that the reactor had not been inspected in recent hours.
“We can’t get inside to check, but we’ve been carefully watching the building’s environs, and there has not been any particular problem,” said Hajime Motojuku, the spokesman for Tokyo Electric.
Japan’s regulators also said early Thursday that radiation levels had decreased steadily overnight. Meanwhile, they continued to evacuate residents within 12 miles of the reactors and provide them with potassium iodide pills to counteract any negative effects of radiation. U.S. military personnel around Japan were among those taking pills after they were recorded with higher than normal radiation levels.
After high radiation levels prevented plant workers from air-dropping water into reactor three on Wednesday, officials hoped the military could make an attempt later Thursday. Reactor four, where a fire broke out earlier in the week, also remained a top priority. The drying pools with spent fuel roads from the two reactors appeared to be the greatest concern, however, because they are not encased as deeply as the active fuel roads in the reactors. Spent fuel at reactors five and six have raised concerns, but the danger doesn’t appear as imminent because the reactors are more intact.
Reactors one and two are both seriously damaged, and it’s unclear what kind of undertaking will be needed to rehabilitate them or completely seal them off.
The 9.0-earthquake that hit last week has caused at least $200 billion in damge, scared off stock investors across the world and left more than 1,400 people dead and tens of thousands more missing. More than two millions lacked either running water or electricity. From India to France, dozens of countries have told their citizens to flee Japan.
Even China, a ferocious builder of infrastructure, said it would suspend its approvals of nuclear power plants until they can be deemed absolutely safe.
Experts from the U.S. Energy Department and the International Atomic Energy Agency were expected to arrive in Japan later Thursday to provide help in assessing the situation at the power plant. Working with the power plant operators, the agencies must decide whether to continue stopgap cooling measures, let the fuel burn and contain the radiation or work to restore broader cooling measures.
TOKYO—Levels of radioactivity from Japan’s damaged Fukushima Daiichi nuclear complex may be above government limits for infants in some areas outside the plant’s 20-kilometer evacuation zone, according to the latest estimate to fuel an international debate over how close civilians should be allowed to the plant.
The new estimate, by a state-funded monitoring body, came as fears over Tokyo’s tap water eased. Tests Thursday also showed radioactive material in a major plant supplying water to the capital has fallen to below the level the government says could pose long-term health risks to infants. Elevated levels in samples from the plant Tuesday and Wednesday sparked official warnings and bottled-water sales.
Japan’s Nuclear Safety Technology Center, a government monitoring group, released the estimate late Wednesday of the cumulative exposure to radiation in zones surrounding the Fukushima Daiichi complex. The estimate covered the 12 days since Japan’s March 11 earthquake and tsunami spurred fires, explosions and spikes in radioactivity levels at the complex.
The estimate—which the center produced by modeling radiation readings collected at various points around the plant—suggested that most areas with radiation that exceeded government thresholds fell within the 20-kilometer evacuation zone.
But the model showed that areas where cumulative exposure over 12 days reached 100 millisieverts—the government’s maximum for infants—extended beyond the evacuation zone. A map based on data from the center showed areas that received a cumulative 100 millisieverts extended as far as about 40 kilometers northeast and south from the plant.
Radiation Levels in Japan
The Japanese government monitors radiation levels around the country. Track these measurements over time.
Government officials said the center’s estimate doesn’t require a larger evacuation, under even the most conservative standards. They said a person would have to have been in the area, and outdoors for the entire time since the March 11 earthquake, to receive that full dose.
Still, the test results demonstrate the uncertainty surrounding the measuring of radioactive emissions from the power plant.
Elevated levels of radioactive elements have been found as far away as Tokyo in its tap water, prompting worries over the nation’s food and water supplies. The U.S. last week recommended citizens come no closer than 50 miles, about 80 kilometers, to the plant, based on its own radiation readings in the area, putting pressure on Japanese authorities to justify their decision to evacuate the area within 20 kilometer of the plant and order those within 30 kilometers to remain indoors.
Tokyo Electric Power Co. said Wednesday it has observed a neutron beam, a kind of radioactive ray, 13 times on the premises of the Fukushima Daiichi nuclear plant after it was crippled by the massive March 11 quake-tsunami disaster.
TEPCO, the operator of the nuclear plant, said the neutron beam measured about 1.5 kilometers southwest of the plant’s No. 1 and 2 reactors over three days from March 13 and is equivalent to 0.01 to 0.02 microsieverts per hour and that this is not a dangerous level.
The utility firm said it will measure uranium and plutonium, which could emit a neutron beam, as well.
In the 1999 criticality accident at a nuclear fuel processing plant run by JCO Co. in Tokaimura, Ibaraki Prefecture, uranium broke apart continually in nuclear fission, causing a massive amount of neutron beams.
In the latest case at the Fukushima Daiichi nuclear plant, such a criticality accident has yet to happen.
But the measured neutron beam may be evidence that uranium and plutonium leaked from the plant’s nuclear reactors and spent nuclear fuels have discharged a small amount of neutron beams through nuclear fission.
the Virginia Institute of Marine Science has published a comprehensive new analysis showing that loss of plant biodiversity disrupts the fundamental services that ecosystems provide to humanity.
